Post on 18-Nov-2020
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Jeremy RenshawProgram Manager
INMM Conference29 January 2020
Recent Advancements in Used Fuel R&D Activities
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Overview of Current R&D Projects
High Burnup Fuel
Demonstration
Nuclear Fuel Thermal
Modeling
HBU Fuel Cladding
Properties
Aging Management
Dry Storage NDE,
Mitigation, and Repair
Collaborative R&D Projects Spanning the Back End of the Fuel Cycle
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Industry Collaboration via ESCP The Extended Storage Collaboration
Program (ESCP) is a collaborative working group organized to identify and address issues related to use fuel storage and transportation
ESCP is made up of utilities, vendors, regulators, national labs, universities, EPRI, and other organizations
These organizations work together to solve global issues
Many/most of the organizations present today are involved in ESCP
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ESCP Overview and Structure
2019 Highlights Workshop on back end effects of ATF Fuel, Thermal, and Decay Heat PIRTs
discussed SONGS work on in situ cold spray repair Merged 3 subcommittees (CISCC, NDE, and
Mitigation & Repair) into 1 subcommittee (Canister Integrity)
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Recent Collaborations Generated by ESCP
High Burnup Demo
Thermal Modeling
Sister Rod Testing Transportation Triathlon
Image credit: Sandia National Laboratories
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HBU Demo provided valuable information to the industry Identified as the #1 priority in the 1st
ESCP Meeting DOE and EPRI co-funded the project and
EPRI served as the project lead HBU Demo gathered various important
data– Temperatures Identified significant biases in thermal
models– Gas composition Verified no fission gas released Identified ~70 cc of water present
DOE funded Sister Rod testing at the National Laboratories to gather key information
Peak Cladding Temperature (Cell 14) = 237°C
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Current Status of HBU DemoHigh Burnup Demo• Cask is loaded and collecting data• Data will support storage license renewal aging
management plans
Extracting More Value than Planned• Data for thermal modeling benchmarks• Rod internal pressure measurements (DOE)• Hydride Reorientation Issue Resolution
Next Steps• Prepare to ship and open cask in 10 years• Support technical basis for long-term storage of HBU
fuel
HBU Demo data available at: https://www.epri.com/#/portfolio/2020/r
esearch_areas/2/061149?lang=en-US
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The High Burnup (HBU) Demo Offered a Unique OpportunityThe HBU demo cask was loaded in Nov. 2017
EPRI Identified an opportunity to perform a blind benchmark of thermal models
EPRI established a thermal modeling subcommittee under the EPRI Extended Storage
Collaboration Program (ESCP)
Using HBU Demo data for international thermal modeling round robin studies
ESCP brought in multiple thermal models for a best-estimate comparison to actual data
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ESCP Thermal Modeling ProgressionES
CP S
teer
ing
Com
mitt
eeCh
air:
Hatic
e Ak
kurt
(EPR
I)
Canister Integrity/Aging Management Subcommittee
Chair: Jeremy Renshaw (EPRI)
Fuel Assembly SubcommitteeChair: Mike Billone (ANL) /
Vice-Chair: Sven Bader (Areva)
Thermal Modeling SubcommitteeChair: Al Csontos (EPRI)
Vice-Chair: Sam Durbin (SNL)
International Subcommittee
David Hambley (NNL) Maik Stuke (GRS), Woo-seok Choi (KAERI), Brady Hanson (PNNL)
Phase IBWR DCS
Simulator
NRC/ DOE Lead
Phase IIaHBU Demo
Cask Round Robin
EPRI Lead
Phase IIbHBU Cask Sensitivity
and Transient Analyses
DOE Lead
Phase IIcPhenomena Identification
Ranking Table (PIRT) Gap
Analysis
EPRI Lead
Phase IIdInt’l HBU
Demo Cask Round Robin
EPRI Lead
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Blind benchmarking temperatures were all biased on the high side
DLBCell 14 (Hottest Cell)
S1S2S3S4Measured
17-20% Decay Heat
Penalty
Max Ambient Temperature Assumption
Conservative Gap Sizes
Added Uncertainties & Regulatory
Margin
Large Biases in Thermal Models
~90°C Bias/ Margin
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Benefits of Improved Thermal Models Occupational dose benefits:
– Temporary shielding restrictions (blankets)– Time limits to keep mating device door open
Dry storage operational benefits:– Storing hotter fuel sooner– More flexible SNF loadouts– Drying time limits and time to boil– Supplemental cooling requirements– Vent surveillance requirements– Fuel and canister degradation mechanisms– Risk informing aging management
Reactor operations/safety benefits:– Reduced SFP temperatures/time-to-boil
Accelerate decommissioning:– Pool to pad sooner (active to passive cooling)
Informs repository loading footprint
Time to Boil Calculations
(SFP)
Fuel Loading into
Storage
Degradation Mechanisms Dry Storage
Repository
Decommissioning
Transportation
Improved Thermal Models Improve Safety
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Thermal Affects the Entire Back End of the Fuel Cycle
Lower Temperatures• ↓ Rod internal pressure• ↓ Stress• ↓ Creep• ↓ Hydride reorientation• ↓ Oxidation
Storage/Transportation• ↓ Fuel degradation• ↑ Understanding of
CISCC• ↓ Dose to workers/public• ↑ Transportability
Decommissioning & Disposal• ↓ Decommissioning costs• ↓ Repository footprint• ↓ Repository costs• ↑ Safety
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-40
-20
0
20
40
60
80
100
1100 1150 1200 1250 1300 1350 1400 1450 1500Clad
ding
Hoo
p St
ress
(MPa
)
Time (Days)
Case 9 Between Cracks
Case 9 At Crack
Case 10 Between Cracks
Case 10 At Crack
Cladding Hoop Stress vs. Time for Different Cladding Temperatures
300°C350°C400°C
Stress relaxation occurs due to creep - most beneficial at higher temperatures
400°C case starts at highest stress, but quickly reduces to the lowest stress in all cases
3 months
1 month
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Cladding Hoop Stress Modeling
Initial peak hoop stress greater than unbonded fuel Stress relaxation occurs in days Peak hoop stress reduces to ~half of initial value
Cracking Pattern 2, Hoop stress starts at 400°C – Initial stress (left) and stress after 60 day hold (right)
Effect of reduced hoop stress on radial hydride concentration
Reduced hoop stress Reduced radial hydrides
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Effects on Cladding
Highly Robust
Cladding↓ Oxidation
rate
↓ Temperatures
↓ Rod Internal
Pressure
↓ Cladding Stress
↓ Hydride reorientation
↑ Cladding ductility
Fuel-clad bonding effects
Stress relief from creep
Ductility from annealing
Electrostatic adherence of
small UO2particles
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Inspection, Mitigation, and Repair Developments
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Aging Management – Maintaining Safety from the Reactor to the Repository
Dry storage systems are needed for longer periods of time than originally anticipated
Aging management will be required to verify continued safe operation
ASME Code Case N-860 initiated to identify inspection and evaluation criteria– Code Case approaching final acceptance
Adopts EPRI Susceptibility Criteria for evaluating CISCC Susceptibility– Defines inspection and evaluation criteria– Sets inspection frequency Inspection frequency adopts a risk-informed
approach (frequency increases or decreases based on inspection results)
– Provides a flowchart for process implementation
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Inspection Video
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Qualitative Overview of NDE Technologies
NowNow, if needed
Timing Technical CapabilityNot Applicable
Now or < 1 year Good Performance / Yes< 3 years Fair Performance / Maybe4+ years or N/A Poor Performance / Not Well Suited
<1 Year
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Robotic Development Upgrade/Retrofit
VT, UT, and eddy current devicesTemp. & Dose MeasurementsSurface CleaningRobot Upgrades
Field Trials
Work with utilities and vendors to deploy and upgrade developed systems
Implementation
Work with Vendors to deploy developed technologies
Item NAC Robot Holtec Robot TN Dual Robot TN Top Vent Robot
VT Inspection Done Done Designed RetrofitEddy current inspection Done Retrofit Done DoneDose Measurement Done Retrofit Retrofit RetrofitRTD Measurement Retrofit Done Retrofit RetrofitThermal Camera Done Desire, not needed Desire, not needed Desire, not neededSurface Cleaning Capability Done Done Done Done
Field Trial(s) Done Done Done, want more Done, want moreSurface Cleaning Test 2nd Tier Need 2nd Tier Need Done 2nd Tier Need
Goal: Develop and Deploy Robots Capable of Performing Required Dry Storage System Inspections
Done
DoneDone
DoneDone DoneDone Done
Removed from List Removed from List Removed from List
Done Done Done
Done
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Improving Safety and Reducing Dose for ISFSI Operations
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Using Drones with AI for Automated Inspection & Analysis to Reduce Worker Dose
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Results available in: 3002015075, 3002015076, 3002013124, 3002008234, 3002010617, 3002010621, & 3002016034
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Together…Shaping the Future of Electricity